ABAETETUBA, Brazil — A 15-year-old girl arrested on petty theft charges was left for weeks in a jail cell with 21 men, who raped her, tortured her and only allowed her food in exchange for sex.

Her screams could be heard from the street. Yet police refused to act, and it took a tip to the local media to finally free her.

Ten police and prison officials and two inmates face up to 20 years in jail if convicted, and a verdict in the trial is expected this month. But nearly a year after the crime, the most shocking element is how normal the girl’s plight seems to many in the sweltering river port city of 78,000 at the mouth of the Amazon where she was imprisoned.

‘‘It was her third time in jail, the only difference was this time someone noticed,’’ said Selma Pinheiro Serrano, a 23-year-old prostitute who knew the girl.

After the uproar of the case, the Para state governor, congressmen, and even the Brazilian president vowed to tackle the problems that caused the assault: callous, corrupt police and a jail system with few separate cells for women. The jailhouse was demolished.

Yet Para, a jungle state twice the size of France stretching inland from Brazil’s northeastern Atlantic coast, still only has six separate cells for women at its 132 jails.

Judge Clarice Maria de Andrade, who approved the girl’s imprisonment, was merely transferred to another jurisdiction without even a censure. It’s also far from clear whether the current judicial inquiry, held behind closed doors because the victim was a minor, will yield any convictions.

The Amazon is littered with such hard-luck stories and towns, where a dearth of opportunity and an abundance of lawlessness are an explosive mixture giving rise to wanton environmental destruction, land grabbing, contract killing, debt slavery and an egregious lack of concern for human rights.

‘‘It just happened to be this girl, but it could have been any one of hundreds here in this city,’’ said Roman Catholic Bishop Flavio Giovenale, who has received death threats for speaking out against police involved in corruption and organized crime. Giovenale says such abuses are so routine in Abaetetuba that when the child welfare group Guardian Council told the police chief there was an underage girl locked up in the jailhouse, he didn’t want to release her. The chief is under judicial investigation and not speaking publicly about the jailing. Guardian Council then went to the local press with the story.

Serrano says her story is much like that of the victim, who is not being identified because she was sexually assaulted. Both come from broken homes where their stepfathers abused them, forcing them out onto the streets to live among prostitutes, crooks and crack dealers preying on the river traffic.

Unemployment in Abaetetuba stands at around 70 percent, and few schools go beyond fifth grade. Drug dealing and prostitution often lure local teens, also leaving them vulnerable to police abuse. After the scandal came to light, Gov. Ana Julia Carepa acknowledged that girls are being arrested in the state expressly to provide sexual gratification for prisoners, ‘‘an unfortunate practice that regrettably has been occurring for some time.’’

She pledged then to try to stop it. But while the state is working on new jailhouses, it has mostly transferred women to other prisons, a move Amnesty International says improves conditions but leaves them even farther from their loved ones.

Abaetetuba is a major transshipment point for cocaine arriving from Colombia and heading off to Suriname and Guyana to the north. The maze of houses on stilts branching out from the town square is littered with drug spots, where a hit of cocaine paste sells for $3.

Many use the upper stories of the tumbling clapboard houses along the docks as brothels. Young girls in flip-flop sandals, skimpy shorts and spandex tops sell their bodies to passing boatmen for as little as $6 a trick.

Others travel by canoe to anchored ships loading up with aluminum, where they can fetch as much as $12.

It was in these environs that the 15-year-old victim was arrested for breaking into a house on Oct. 21, 2007.

Days after the scandal broke, reports of other women jailed with men began popping up across Brazil — most notably a 23-year-old woman forced to share a cell with 70 men in Paraopebas in southern Para.

None of the girls along Abaetetuba’s docks claimed to have been locked up in a cell full of men, though several could describe the jail where the girl was kept and a corridor without a toilet used to hold women. Nor did many of the girls express sympathy for the victim because she was a thief — a line they claim they would never cross.

‘‘Lots of these kids rob. The girl’s problem was she kept getting caught,’’ he said.

When she was jailed, no one noticed she was missing because her parents were separated and living out of town, Franzini said.

Besides repeated rapes, the girl said she was tortured with lit cigarettes on her fingers and bare feet, according to the newspaper O Estado de S. Paulo. Jailers shaved her head to disguise her as a boy in a cell with men.

The girl said her only reprieve from rape came on Thursdays — when intimate visits were allowed — and things ‘‘calmed down,’’ Estado reported.

Franzini went with the girl after her release to talk with prosecutors and later to the airport where she was flown to Brasilia, the nation’s capital. There she was put in a witness protection program.

‘‘She had to tell and retell her story to various prosecutors and every time her story was consistent. She said who shaved her head to make her look like a boy, who had sex with her and who didn’t and who burned her feet and fingers with cigarettes,’’ Franzini said.

He hears the victim has successfully completed a detox program, is off drugs and back in school at a secret location.

But other young women, like Serrano, will likely never escape.

‘‘Sometimes, I go away to the country to try and clean myself up, but after a few days I can’t stand it anymore,’’ Serrano said. ‘‘I’m an addict, and selling my body is the only way to pay for it.’’